Switch-contact



c. H. RIPPL.

SWITCH CONTACT.-

APPLICATION FILED MAY 23. I917.

1 3 34 554 Patented Mar.23,1920.

I N VEN TOR.

A TT ORNE Y.

UNITED STATES PATENT OFFICE.

CHARLES H. RIPPL, OF CLEVELAND, OHIO, ASSIGN OR TO THE ELECTRIC CONTROLLER &

MANUFACTURING COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

SWITCH-CONTACT.

Specification of Letters Patent.

Patented Mar. 23, 1920.

Application filed May 23, 1917. Serial No. 170,376.

To all whom it may concern:

Be it known that I, CHARLES H. RIPPL, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and use-- ful Improvements in Switch-Contacts, of which the following is a specification.

This invention relates to electric switches, and particularly to switches which have their contacts immersed in oil.

The contacts of switches adapted to carry comparatively large currents are usually so constructed that the making and breaking of the current occurs at parts of the con-' tacts other than the surfaces thereof which carry the current continuously after the switches close. This provision is usually made because it has been found that it increases the continuous current-carrying capacity of the contacts. When the mutually engaging contacts are each made of a single piece of material, such as copper, it is customary to cause the contacts to slide upon each other during their closing and opening operations. In closing, after the contacts first touch at their circuit-making parts, they slide upon each other until the continuous current-carrying parts thereof have come into engagement; and in opening, the contacts first slide upon each other until the current-breaking parts have come into engagement, and then these parts separate to break the current.

When contacts of this kind are immersed in oil, for well-known purposes, such as for instance to facilitate breaking the current arc, I have found that the sliding movement causes excessive wear on the contacts, the wear being much greater than usually occurs upon the same kind of contacts operating in the open air. This excessive wear maybe explained as follows: At the time of making or breaking the current at the contacts, the presence of the oil seems to localize or concentrate the action of the current upon a very small area of the contact surface. thereby burning a small rough spot on the contacts; the friction of the sliding movement is concentrated on this small rough spot and rubs it off. A repetition of this action rapidly wears away the material of the contacts.

I have found that this excessive wear may be obviated by so designing the contacts that during the closing and opening processes the contacts instead of sliding upon each other in going from the current-makeand-break position to the current-carrying position, or vice versa, will have a rocking, or substantially rocking movement upon each other.

I have found by experiment that the working life of the contacts may in this way be doubled or even trebled.

The principal object, therefore, of this invention is to provide switch contacts which, during their opening and closing processes, have a rocking or substantially rocking movement upon each other, whereby the wear that would otherwise occur upon the contacts is reduced or obviated. Other objects will appear hereinafter.

Referring to the accompanying drawings, Figure 1 is a side view, parts being shown in cross section and broken away, of a switch inclosed in an oil-filled container and embodying my invention, the switch contacts being s own in open position; Fig. 2, a view similar to Fig. 1, with parts omitted, and showing the contacts in the contact-making or contact-breaking position; and Fig. 3, a view similar to Fig. 2, but showing the contacts in the current-carrying position.

Referring to Fig. 1, I have shown at 10 a tank or container, and at 11 a cover thereon. The tank 10 is adapted to be filled with oil up to the oil-level line 12, but the oil itself is not shown for the sake of the simplicity of the drawing. The switch which I have chosen to illustrate my invention is an electro-magnetic switch having the energizing winding 13. The magnetic circuit energized thereby comprises the stationary yoke 14 having the horizontal portion 22, the core 15, the movable switch-arm 16 pivoted to the yoke 14 at 17 and the loose plunger 18 in the switch-arm 16 opposite the core 15. lVhen the winding 13 is energized, the arm 16 is rotated about the pivot 17 in the clockwise direction by the mag netic pull in the gap 19 between the ends of the core 15 and the loose plunger 18 in a'mannerwell understood. The travel of the plunger 18 is stopped upon the end of the core 15, but the arm 16 may over travel slightly for a purpose to be described; this feature forms no part of my invention, and is fully described in patent to H. E. Frost, No. 1,053,489, dated February 18, 1913.

When the parts are in their normal, or

open positions shown, the arm 16 is held in pivoted at 26 to the bracket 27. A com pression spring 28 at all times exerts a clockwise torque upon the arm 25 and the contact 24. One end of the spring presses upon the shoulder 29 on the switch-arm, and the other end presses upon the shoulder 30 on the bracket. The clockwise movement of the switch-arm is limited by the engagement of the tail piece 31 of the switch-arm with the stop 32 on the bracket. Studs 33 and 34 are provided on the bracket 27 and the magnet yoke 14, respectively, to which electrical connections maybe made. The pivots 17 and 26 are on opposite sides of the point of engagement of the contacts.

When the contacts 23 and 24 have been brought into engagement upon energizing the winding 13, the switch may be used to close an electric circuit, the current flowing through the stud 34, the yoke 14, the flexible conductor 35 (which shunts the pivot 17), the arm 16, the contacts 23 and 24, the arm 25, the flexible conductor 36 (which shunts the pivot 26), and the bracket 27 to the stud 33.

The contacts 23 and 24 are preferably exactly alike, butone is turned upside down with respect to the other. The contact portions of each of these contacts consists of two contact surfaces lying in planes at an angle with each other, the cont-act surfaces of the contact 23 being shown at 37 and 38, and the contact surfaces of the contact 24 being shown at 39 and 40. When the switcharm 16 moves in the clockwise direction to close the switch contacts 23 and 24, the contact surface 38 of the contact 23 engages the contact surface 40 of the contact 24, as shown in Fig. 2. The wear caused by the closing of the contacts, whether mechanical (due to the shock of impact) or electrical (due to momentarily bad contact) occurs upon these contact surfaces 38 and 40. As the switch arm 16 continues to move in the clockwise direction, the contacts 23 and 24 roll,.or rock, upon each other from the position shown in Fig. 2110 that shown in Fig. 3,.

bringing the contact surfaces 37 and 39 into engagement. These surfaces remain in engagement, and since the continuous flow of current is through the electrical contact between these current-carrying surfaces 37 and 39, the highest possible current-carrying' capacityof the contacts is maintained. When the winding 13 is deenergized to open the switch contacts, and the switch arm moves in the counter clockwise direction, the con tacts move from the position shown in F ig'. 3 to that shown in Fig. 2. The further movement of the arm 16 ultimately separates the contacts, which move to the positions shown in Fig. l, breaking the current on the surfaces 38 and 40.

The contact 24 is held resiliently against the contact 23 by the compression spring 28. During the closing of the contacts, the impact of the contact 23 upon the contact 24 tends momentarily to drive the contact 24 away from the contact 23 and draw an are on the contacts; this is prevented by giving the contact 23 a momentary overtravel by means of the loose plunger 18 above described.

While the movement of the contacts 23 and 24 upon each other is substantially a rolling, or rocking, movement, it may sometimes be necessary, in finding suitable and economical locations for the pivots 26 and 17, to allow some sliding movement of one contact upon the other.

My invention is not limited to an electromagnetic switch, since my invention maybe embodied in switches operated manually or otherwise.

I claim A 1. In a switch, a pair of contacts, having mutually engaging contact-making and ourrent-carrying portions, and pivotal supports for the contacts arranged to cause the arcs of their movements to practically coincide while moving from one pair of engaged portions to the other, the pivotal support of one contact being outside the circle described by the radius drawn from the other pivotal support to the contact carried thereby.

2. In a switch, two contacts each having two faces, and pivotal supports for the contacts arranged to cause the contacts to be engaged at one pair of faces and to move to the other pair of faces without substantial slide during the transition movement, the pivotal support of one contact being outside the circle described by the radius drawn from the other pivotal support to the contact carried thereby.

3. The combination of an oil-tank, oil therein, two switch contacts in the oil, each contact having two faces, and pivotal supports for the contacts arranged to cause the contacts to be engaged at one pair of faces and to be moved so as to be engaged at the other pair of faces without substantial travel of one on the other during the transitional movement.

4. The combination of an oil-tank, oil in the tank, two contacts in the oil, each con tact having current-make and break portions and current-carrying portions, "and pivotal supports for the contacts arranged to cause one pair of said portions to be moved into mutual contact and thereafter the other pair of said portions to be moved into contact by a substantially rocking movement of the contacts upon each other without substantial travel of one contact on the other.

5. The combination of an oil-tank, oil therein, two contacts each having two faces, and pivotal supports for the contacts arranged to cause the contacts to be engaged at one pair of faces and to move to the other pair of faces without substantial travel of one contact on the other during the transition movement, the contact-making and current-carrying portions on each contact forming an angle projecting toward the other contact, the contacts rocking with their angles in mutual engagement while moving from one pair of portions to another.

6. The combination of an oil-tank, oil

therein, two contacts each having two faces, and pivotal supports for the contacts arranged to cause the contacts to be engaged at one pair of faces and to move to the other pair of faces during the transition movement, the contact-making and currentcarrying portions on each contact forming an angle projecting toward the other contact, the contacts rocking with their angles in mutual engagement while moving from one pair of portions to another and having their contacting portions traveling substantially equal distances each side of a line joining their centers of travel.

Signed at Cleveland, Ohio, this 21st day of May, 1917.

CHARLES H. RIPPL. 

